玉米丝黑穗病是我国春玉米产区的重要病害之一,其发生轻重与播种至三叶期的土壤湿度和温度有密切关系。在这段时间,土壤湿度大、温度低,发病则轻,反之则重。据贵州省威宁县植保站调查记载,4月下旬至5月上旬(当地玉米播种至出苗的时期)的降雨量,1979年为14.3毫米,1980年为36.6毫米。玉米丝黑穗病的发病率两年分别 Corn smut is one of the most important diseases in the spring maize producing areas in China. The occurrence of maize smut is closely related to the soil moisture and temperature in the period of sowing to the three-leaf stage. During this time, soil moisture, low temperature, the incidence is light, otherwise the weight. According to a survey conducted by Plant Protection Station in Weining County, Guizhou Province, rainfall in late April to early May (the period from local corn sowing to emergence) was 14.3 millimeters in 1979 and 36.6 millimeters in 1980. The incidence of maize smut two years respectively